The polarization switching kinetics were measured at the nanoscale in continuous thin films of a ferroelectric copolymer of vinylidene fluoride and trifluoroethylene. The dependence of the switching rate on voltage for a 54-nm thick film exhibits extrinsic nucleation and domain-growth type kinetics with no true threshold coercive field, and is qualitatively different from the behavior of an 18-nm thick film, which exhibits intrinsic switching kinetics, and a true threshold field. The results are consistent with studies of thin film capacitors of much larger area and with a recent refinement of the theory of the critical size for intrinsic switching.
Gaynutdinov, R.; Minnekaev, M.; Mitko, S.; Tolstikhina, A.; Zenkevich, A.; Ducharme, Stephen; and Fridkin, V., "Polarization switching kinetics in ultrathin ferroelectric barium titanate film" (2013
b s t r a c tThe investigation of polarization switching kinetics in an ultrathin barium titanate film reveals true threshold switching at a large coercive electric field, evidence that switching is of intrinsic thermodynamic nature, rather than of extrinsic nature initiated by thermal nucleation, which has no true threshold field. The switching speed of a 7 nm thick epitaxial film exhibits a critical slowing as the threshold is approached from above, a key characteristic of intrinsic switching. In contrast, a bulk crystal exhibits nucleation-initiated switching, which has no threshold, and proceeds even at fields well below the nominal coercive field, which was determined independently from the polarization-electric field hysteresis loop. Previously, this phenomenon was only reported for ultrathin ferroelectric polymer Langmuir-Blodgett films. Since both the thermodynamic coercive field and the intrinsic switching kinetics are derived from the mean field theory of ferroelectricity, we expect that these phenomena will be found in other ferroelectric films at the nanoscale.
We investigated the properties of the IR signal generated through coherent Raman scattering involving the Q(1) transition (v = 0, J = 1 ! v = 1, J = 1) of a hydrogen molecule in the presence of the quasi-static electric field of the sliding discharge propagating along a ferrite surface in a hydrogen atmosphere. The results of time-resolved polarization-sensitive measurements performed on this signal were employed to determine the parameters of the electric field in the sliding discharge. These measurements showed, in particular, that the propagation of the discharge leader along the ferrite surface is accompanied by the rotation of the vector of the quasi-static electric field.
An electron beam source based on a dielectric barrier discharge and a perforated anode working in a dense gas is described. Electron beams with current densities up to 60 A/cm2 and pulse durations of 150 ns were generated. Stable operation of the device at a repetition frequency of 200 Hz has been demonstrated.
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